The present invention relates to a thread drawing-off device for an open-end spinning device, having a pair of draw-off rollers comprising an overmounted pressure roller which cooperates resiliently with a driven roller projecting across the front of the pressure roller, and a method which may be carried out using this device.
In order to insert the thread into the clamping line of a pair of draw-off rollers comprising a driven roller and a pressure roller lying resiliently against the latter, it is known to provide the front edge of at least one roller with an annular chamfer and to insert the thread in the area of the clamping line at the front of the pair of draw-off rollers, so that it is automatically disposed in the pair of draw-off rollers as a result of the winding tension (German Auslegeschrift No. 1.685.994, FIG. 6 and 7). It is also known for this purpose, to provide the periphery of the pressure roller with a notch-shaped recess which moves into the path of the thread, grips the thread and conveys it into the clamping line of the pair of draw-off rollers (German Auslegeschrift No. 1.560.336). In both cases, there is a certain time lapse before the thread is disposed in the clamping line. The thread is introduced into the pair of draw-off rollers either only after the notch-shaped recess has traveled a certain distance, or after overcoming the clamping pressure of the two rollers. This leads to slipping, roughening, damage or breakage of the thread and, therefore, to an undefined insertion of the take-off thread. In particular, in the case of high thread take-off speeds, as is usual nowadays with open-end spinning machines, this leads to a non-uniform beginning of the thread take-off which results in variation of number in the spun thread.